The continued proliferation of multimedia technologies has led to exponential growth in the number and variety of devices capable of processing digital video data. Similarly, the ease with which video data may be copied and distributed without authorization has also increased, which in turn has led to various copy protection strategies and improved Digital Rights Management (DRM) techniques. The inherent challenges of efficient storage and distribution of video data, in turn, have inspired much innovation in the area of scalable video coding and video transcoding.
In various applications, such as digital broadcast and cable television (TV) systems, video data is normally encrypted before transmission for security (i.e., to prevent unauthorized use of the content). Near the receiving end of these transmissions, such as in-home video redistribution, it is common to bit-rate transcode the video bitstream for efficiency (i.e., to achieve optimum utilization of available bandwidth). “Transcoding” is the direct digital-to-digital data conversion from one encoded format to another encoded format (i.e., decoding to an intermediate form and then re-encoding) such as, for example, from a high-quality large-size format to a lower-quality smaller-size format. However, when a video signal is decrypted, transcoded (from the original encoded format to the target encoded format), and then re-encrypted to complete transmission, there is a period of time where the video data is relatively unsecure (i.e., unencrypted) and vulnerable to unauthorized use.
While some transcoding solutions attempt to mitigate this risk by performing transcoding using only trusted and tamper-proof devices, such devices are relatively expensive due to the increased cost of manufacturing inherent to such devices, and these increased costs of production have limited the widespread utilization of such trusted and tamper-proof devices. Accordingly, there is a need for a transcoding approach that maintains security of the video data during the transcoding process.